The Programming Languages Zoo

miniprolog

Miniprolog is a minimalist prolog interpeter. It does not contain cuts, arithmetic, lists, or equality – just basic Horn clauses.

The terms of the language consist of:

• constants, which are strings of alphanumeric characters, starting with a lower case letter.
• variables, which are strings of alphanumeric characters, starting with a upper case letter.
• composite terms of the form f(t1, ..., tn) where f is a constant and t1, …, tn are terms.

Examples of terms are: x, y, X, A, son(abel, adam), less(X, plus(X, one)).

You may type in assertions and queries. An atomic assertion is written as a term followed by a period,

assertion.

an inference rule (complex assertion) is written as

goal :- subgoal1, ..., subgoalN.

where assertion, goal, subgoal1, …, subgoalN are terms. A query is written as (including the “?-”)

?- query.

where query is a term. You may type assertions and queries at the command line or place them in a file. See the enclosed examples.

Sample session, see also the file example.miniprolog.

miniProlog -- programming languages zoo
Type Ctrl-D to exit
miniProlog> it_is_raining.
miniProlog> no_umbrella.
miniProlog> i_am_wet :- it_is_raining, no_umbrella.
miniProlog> ?- i_am_wet.
Yes
miniProlog> ?- i_am_dry.
No
miniProlog> child(luke, vader).
miniProlog> child(leia, vader).
miniProlog> ?- child(X, vader).
X = luke
more? (y/n) [y] y
X = leia
more? (y/n) [y] y
No
miniProlog> sibling(X,Y) :- child(X,Z), child(Y,Z).
miniProlog> ?- sibling(A,B).
A = luke
B = luke
more? (y/n) [y] y
A = luke
B = leia
more? (y/n) [y] y
A = leia
B = luke
more? (y/n) [y] y
A = leia
B = leia
more? (y/n) [y] y
No
miniProlog>